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By J Watson

Electronic detonator technology has been under development for the last two decades. Currently, there are a number of systems commercially available with several others still under development, each with its own unique features. This technology can offer a significant advantage to the drill and blast engineer through their ability to initiate an explosive charge at the æplannedÆ time. This new technology has created huge interest within the drill and blast community and also raised their expectations to produce better blasting outcomes. In many cases, specifications (or even expectations) of desired blast results are not properly defined. Interaction between the input variables (rock mass characteristics and blast design) and results (fragmentation, throw, damage, ground vibrations, etc) and their mechanisms, or relationship to one another, are not very well defined or understood. That is why rock blasting is still considered by many as an art rather than science. With one of the few remaining variables (cap scatter) now controllable, todayÆs blaster finally has the ability to apply science to his trade. Even though electronic detonators are available and becoming more commonly used, current field practices are not always conducive to extracting or deriving the maximum benefit from this new technology. In the authorÆs opinion, the following need to be understood to derive and sustain the maximum value: clear definition or specification(s) of desired outcomes from a given blast; impact of different features in an electronic detonator system (precision, accuracy, flexibility, reliability, etc) and their impact on the desired blasting outcomes; interaction of blast design variables (energy, energy distribution, timing, blast geometry) and their impact on desired outcomes; impact of rock mass variability and quality of blast implementation on the desired blasting outcomes; and critical need to utlilise appropriate tools and systems in order to measure and quantify benefits.In the authorÆs opinion a scientific implementation process is the key to derive the benefits. This paper analyses the industryÆs preparedness to derive the benefits from this technology and proposes a scientific methodology to understand, evaluate and sustain the value from this technology.

Jan 1, 2004

By D L. Decker, G C. Miller, C Papelis

Arsenic, often associated with precious metals ore deposits, is a major contaminant released during large-scale gold mining. Because of the complex oxidation/reduction and sorption behaviour of As, prediction of the long-term mobility of As in pit lakes is uncertain. The behaviour of As in pit lakes is investigated in this paper by conducting a series of laboratory experiments where As is allowed to adsorb onto pit lakes sediments. Experiments were conducted over a range of pH with both As(III) and As(V) allowed to adsorb onto sediments collected from existing pit lakes found in the three main orebody types in Nevada, USA; porphyry copper, quartz-adularia gold, and Carlin Trend type gold deposits. Results from adsorption experiments show that As(V) and As(III) adsorption is strongly pH dependent with higher uptake at pH 5 and lower uptake at pH 9 for As(V) and higher uptake at pH 9 and lower uptake at pH 5 for As(III). This behaviour, as expected for oxyanions, has been described previously for agricultural soils, iron oxides, and Carlin Trend heap materials. Maximum adsorption of As(V) for the Carlin Trend type gold sediment was 3.0 g/kg at pH 5, 2.0 g/kg for the quartz-adularia sediment, and 0.9 g/kg for the copper porphyry sediment. Maximum adsorption of As(III) for Carlin Trend type gold sediment was 2.5 g/kg at pH 9, 2.2 g/kg for the quartz-adularia sediment, and 2.1 for the copper porphyry sediment. Adsorption isotherms are non-linear and show Freundlich isotherm behaviour. Variations in sorption between the different pit lake sediments under similar conditions can be explained by differences in the elemental composition of the sediment. Most rock forming elements from XRF analysis are similar in quantity except for Fe. The Fe content is highest in the Carlin Trend type gold deposit sediments and lowest in porphyry copper deposit sediments and is the third most abundant element in all three sediments. The Fe content of the sediments correlates well with the amount of As sorption seen in the laboratory experiments.

Jan 1, 2003

By M Biesinger, R St C Smart

Diagnosis of the surface chemical factors playing a part in flotation separation of a value sulfide phase requires measurement of the hydrophobic and hydrophilic species that are statistically different between the concentrate and tail streams. Statistical methods, based on the monolayer-sensitive time of flight secondary ion mass spectrometry (ToF-SIMS) technique, have been developed towards this ultimate aim by measuring hydrophobic species (collector ions, dimers and metal complexes, polysulfides) as well as hydrophobic metal ions, precipitates and added depressant species. Reliable identification of specific mineral particles is central to this statistical analysis. A chalcopyrite/pyrite/ sphalerite mineral mixture conditioned at pH 9 for 20 minutes to study transfer of Cu from chalcopyrite via solution to the other two mineral surfaces, since this mechanism can be responsible for their inadvertent flotation in copper recovery, showed no statistical difference in the copper intensities on pyrite and sphalerite (selected from Fe and Zn images) after this conditioning. Principal component analysis (PCA) identifies combinations of factors strongly correlated (positively or negatively) in images or spectra from sets of data. In images, PCA selects these correlations from the mass spectra recorded at each of 256 ¦ 256 pixels in a selected area of particles. In the image mode, PCA has proved to be a much better method of selecting particles by mineral phase with clearer definition of particle boundaries due to multi-variable recognition. It has clearly separated a statistical difference in copper intensities between the sphalerite and pyrite phases. The PCA method has been applied to concentrate and tails samples collected from the Inco Matte Concentrator demonstrating extensive CuOH and NiOH transfer between the chalcocite (Cc) and heazlewoodite (Hz) minerals. Statistical differences illustrate the important discriminating depressant action of NiOH in flotation despite the activation of Hz by Cu transfer. The adsorption of the collector at specifically-identified Cu sites has been elucidated by the study. Importantly, the statistical analysis has been able to confirm some mechanisms and deny others proposed to control recovery and selectivity giving more focus on the control factors.

Jan 1, 2005

Krupp Polysius AG, FRG, in close cooperation with Prof. Dr. K. Schoenert, FRG have developed the principle of the high pressure grind- ing roll POLYCOM. The POLYCOM mill basically consists of two counter-rotating rolls of large diameter and relatively small width, one of which is fixed and the other moving in slide blocks. The pressure required for comminu- tion is applied via the sliding roll by a powerful hydraulic system. The comminution takes place between the rolls under high pressure in the bed of material by nipping and compacting. The top feed size-depending on the rolls diameter -may be as coarse as conventional secondary crusher feed and the product is a compacted cake containing a high amount of fines created by micro-cracking. The amount of fines depends on the pres- sure (grinding force) applied. Operating results show that even in wet griding circuits capacity increases at downstream connected grinding mills of up to 100010 can be accomplished with an interconnected POLYCOM machine and energy savings of up to 25070 may be achieved depending on application. POLYCOM can be used in existing grinding plants for low-cost upgrad- ing of capacities but also as an advanced alternative to conventional crush- ing and grinding equipment in open or closed circuit configuration. A single industrial size 2.8m roll diameter POLYCOM machine may be fed with top feed size of up to 200mm and produce a finish product as fine- grained as known from rod and ball mills but with less energy consumption. Meanwhile, the POLYCOM high pressure grinding roll has established itself world-wide in the cement industry and is now entering the mining industry. POLYCOM machines are currently designed in industrial standard sizes of 1.0m to 2.0m rolls diameter and drive units of up to 2400 kW. This paper includes: principles of high pressure grinding, main fea tures of the POLYCOM machine, results of tests on various materials including Australian gold and copper ores carried out at the POLYSIUS research centre in Germany. Some examples of industrial applications of high pressure grinding will also be presented.

Jan 1, 1988

By Hood M

Rock cutting excavation technologies and particularly continuous excavation technologies, can offer benefits in the areas of reduced costs, higher revenue and increased safety in a variety of mining situations. Non-explosive rock excavation technologies for example, can deliver significant benefits in the areas of dilution and improved ground support (no overbreak). This paper is an attempt to focus on the development and future of alternative rock breaking technologies and to provide some insights as to why and how we should proceed in this direction. The market size for underground hard rock excavation technologies is examined. A short review of the evolution of various rock excavation technologies in terms of cost and production rate is given and a summary of the state-of-the-art technology is presented. Mechanical excavation technologies (TBM) have very high production rates compared to D&B and the gap is widening, however, they have not been successfully applied to mining applications. Operating costs for mechanical and D&B systems have been dropping over time, however, D&B costs are the lowest. Given the current state of knowledge it appears that with regard to hard rock underground metalliferous mining that R&D efforts should be focussed in the following areas - disc cutter tool development (materials and design; operation; presentation to the rock surface), hybrid cutting systems (consisting of water jets and disc cutters) and development of pressurised hole breakage technologies. It is also possible that two techniques known as the pulsed laser and pulsed water jets may have some potential. The generally agreed specifications for a widely applicable underground hard rock excavating machine are - disc cutter based, a minimum production rate of 100 t/h, be flexible, manoeuvrable and deployable, weight of less than 100 tonnes and be economically competitive with D&B in rocks over 150 MPa UCS. Such a machine would seriously challenge the position of conventional D&B in a wide range applications and provide some of the benefits of mechanisation and automation that the mining industry is pushing so hard for. However, technology developments in the D&B area are not static and hence the target is moving and is increasingly difficult to overtake.

Jan 1, 1995

The Teutonic Bore deposit lies in a major greenstone belt within the Archaean Yilgarn craton of Western Australia. It occurs towards the base of a suite of tholeiitic basalts, some 100 m above a felsic volcanic pile of rhyolitic composition. Sediments comprise a minor, albeit important, percentage of the mine stratigraphy.The deposit consists of a single, steeply dipping lens of massive sulphides totalling 1.4 million tonnes grading 4.16 per cent Cu, 16.4 per cent Zn, 1.22 per cent Pb and 203 g/t Ag. In addition, cross cutting "stringer" mineralisation in the footwall contributes a further 0.75 million tonnes at 2.38 per cent Cu, 1.92 per cent Zn and 52 g/t Ag to the mining reserves. Principal primary sulphides in massive and disseminated mineralisation are sphalerite, pyrite, chalcopyrite and galena, while minor amounts of arsenopyrite and argentiferous tetrahedrite are also present. Weathering has affected the primary mineralogy down to at least 90 m, resulting in a strongly leached oxide profile to about 85 m, overlying a thin, erratic zone of chalcocite supergene enrichment.Lateral metal zoning is marked both in massive sulphide and stringer mineralisation, with Cu/Zn ratios decreasing away from the centre of the orebody. Alteration is well developed in association with footwall stringer mineralisation, changing from a central Fe-Mg carbonate, chlorite and silica alteration zone below the massive sulphides to an outer halo of sericitisation. The spatial distribution of these minerals is patchy. Geochemically, the footwall alteration zone is characterised by central Cao, Na20 and Sr depletion (with less regular enrichment of SiO2 , Fe and MgO), surrounded by a peripheral zone of K20 enrichment.Evidence supports a classic volcanic-exhalative origin, involving submarine discharge on the flanks of a rhyolitic dome and accumulation of the massive sulphides in a local palaeotopographic depression. The sulphides overlie their feeder zone as shown by alteration and stringer mineralisation. Tholeiitic wallrocks are thought to be genetically unrelated to the mineralising solutions, although their presence as a cap over the felsic volcanics may have permitted the build up of a circulating metalliferous brine system prior to sulphide deposition.

Jan 1, 1984

The general types of industrial behaviour of liberated valuable sulfide minerals in the 0 - 10 ¦m size fraction are described and tests to explore on site at a concentrator the general nature of any deficient behaviour are discussed. In addition, the general types of behaviour of the gangue minerals in this size fraction are also described in terms of their mechanisms for recovery. These behaviours are also discussed in terms of the type of grinding device and grinding environment in which they were produced and the target grinding product size. Major recent improvements in the industrial capabilities of grinding devices are discussed.Present difficulties in characterisation of particles in the 0 - 10 ¦m range are described and desirable improvements for the future are outlined. Further, desirable improvements for industrial processing of valuable minerals in this size range are discussed along with some remedial actions.

Jan 1, 2005

By G R. Ballantyne, G Lane

Dry milling circuits that include high pressure grinding rolls (HPGR) or vertical roller mills (VRM) and air classification have replaced dry ball milling in cement production, but how do they compare to wet milling and classification circuits in mineral processing plants? Two case studies are presented that compare the energy efficiency, wear, liberation and capital cost of dry and wet milling circuits. In both case studies the VRM and HPGR consume half the energy of a wet tumbling mill for the same duty. However, the dry classification system tends to significantly erode the energy benefits. A number of improvement opportunities are presented that have the potential to improve the energy and capital efficiency of dry milling circuits. These improvement opportunities focus on the dry classification system that consumes significant energy in heating and fan power requirements and requires a large proportion of the footprint.

Aug 24, 2022

By J A. M Luz, A T. Bernardes

HukkiÆs law is an empirical law, which does not take into account several events of energy loss during the fragmentation processes. Since experimental results are very difficult to obtain, for a large range of fragment sizes, the verification of the law is very difficult. The relation between fractures and fragmentation processes with fractal geometry was proposed some decades ago. Empirical laws known in this context show basic features of fractal geometry, mainly self-affinity and power law behaviour. Thus, in this work a model was developed to simulate the fragmentation process and to check the relation between energy consumption and fragment sizes. The model is represented on a regular lattice. Links can represent pathways for fracture processes. The events of fragmentation have energy given by a probability distribution function. In the model there is no mass loss. Propagation of fractures occurs as self-avoiding random walks on the regular lattice.

Sep 26, 2011

By R O. James

The usual focus of papers on fatty acid collector action in non-sulfide flotation is on the adsorption of the carboxylate and/or neutral molecule species at the mineral-solution interface. Little attention is paid as to whether or not the solution conditions correspond to true solutions, micellar and other self-assembly objects or precipitates. Our examination of the solution chemistry of the important fatty acid collector, oleic acid, has revealed that many, if not most investigators set their experimental conditions to be in micellar or precipitate domains while arguing, often by implication, that they have only solute species present. We have investigated the equilibrium solution domains usually encountered in studies of oleic acid flotation of such minerals as barite, calcite and fluorite. The alkaline earth-fatty acid and liquid oleic acid precipitate phases exert a strong influence on the solution chemistry, a fact not often appreciated in many studies.

Jan 1, 2005

Approximation of Surface Area of Fines in Blast Induced Fragmentation The surface area of fragmentation, especially in the finer size fractions, is a useful property to characterise the mechanisms of rock breakage. In the past, researchers have made assumptions with regard to the shape of fragments in order to estimate surface area, such as that all fragments are the same shape or all fragments are spheres. Often these assumptions were developed with inappropriate measures and returned considerable variability and error for the calculation of surface area. This paper reports a model to estimate fragmentation surface area from sieve sized raw data and a density measurement, with experimental validation down to a size fraction of -45 + 38 ?m in a range of rock types. After characterisation of particle shape, a range of fragment shapes was found to be in each size fraction. Nevertheless, in the ?2 sieve series the average fragment mass, volume and the size fraction standard deviations could be predicted reasonably accurately. Ellipsoid geometry was used to describe particle shape. Using these parameters and the number of fragments (also predicted) in each sieve size the individual surface area of each fragment was simulated.

Sep 13, 2010

By S Moradi

The aim of this study was to investigate the possibility of leaching zinc from the tailing (-2 mm) of Angouran flotation plant using sulphuric acid. The tails were first calcined at 800¦C for one hour. The effect of factors such as stirring rate, temperature, initial acid concentration and solid/liquid ratio, on zinc extraction were studied. The results obtained show that at the best conditions, about 91 per cent of zinc were leached using a stirring rate of 800 rpm, a reaction temperature of 50¦C, a 30 minute reaction time, a 100 g/L initial sulphuric acid concentration and solid:liquid ratio 1:6 g/ml. The P85 of the feed material was about 150 ¦m and acid consumption was 600 kg/t.

Jan 1, 2002

By R L. Brathwaite

As part of an investigation of the deep structure of the Waihi Basin, an extensive set of resistivity measurements was recently collected by DSIR Geology & Geophysics. The objective of this work is to map deep resistivity changes throughout the Waihi area in order to contribute to a better understanding of the regional geophysical structure. This research is also aimed at improving techniques for locating 'deposits of epithermal mineral resources, and helping to establish their origin and genetic relationship to fossil geothermal systems.   The results indicate that the basin south of Waihi is underlain by an extensive layer of low resistivity, modelled as a 5ohm-m layer several hundred metres thick. Lake sediments (mudstones), as exposed in the south western part of the basin, near Waitawheta, are the most likely source of this low resistivity layer, although hydrothermally altered clays and/or elevated temperatures are other possible causes. Strong northeast trending anisotropy is also observed, implying structural links from Waitawheta through to Golden Valley. The observed resistivity pattern is consistent with a æburied calderaÆ or æfaulted depressionÆ structural model for the basin, as inferred from gravity and magnetic data.

Jan 1, 1991

By Wauchope AMH

Arsenic residues from BHAS Refinery operations are currently treated to form a calcium arsenic compound and stored in lined dams on site. Laboratory and large scale work on these residues has resulted in the development of a hydrometallurgical process for production of arsenic trioxide. The process also recovers the material from the storage dams. The residues are hot water leached to produce an alkaline arsenic liquor. This liquor is mixed with material from the storage dams and lime to form a calcium arsenic precipitate. The precipitate is then reacted with sulphuric acid to form gypsum for return to the main plant, and an acidic arsenical solution. Metallurgical gas containing 3-6% sulphur dioxide is bubbled through the solution and on cooling arsenic trioxide is precipitated. The product contains in excess of 95% arsenic trioxide. Installation of a plant at Port Pirie based on this process is being evaluated by BRAS.

Jan 1, 1984

Mineral exploration management has undergone major changes particularly in the last decade. Parallel to these changes in management, and partially responsible for them, have been the changes in governmental laws and regulations at both National and State levels reinforced by a highly competitive climate created by the exploration boom in Australia. The influence of overseas methods and approaches have been married to the Australian techniques resulting in a management climate which is not only familiar with the technical aspects of exploration, but is also familiar with the personnel, economic and legal phases associated with the expenditure of very large sums of money. The utilization of all the geosciences coupled with mathematical models and computer techniques for pre-selection and assessment of areas are now normal aids used in management decisions. Management techniques developed and being developed will ensure that successful exploration will be carried out if sufficient incentives are guaranteed.

Jan 1, 1974

To grow a mining company today is seen to be challenged by the reduced interest in resources companies by the financial markets, the complexity of native title and a somewhat depressed commodity cycle. However, the opportunity to grow production and sales in a mining company are as numerous as they have ever been. It is the challenge of growing significant shareholder value that is difficult. The distinction between growth in æcompany sizeÆ and growth in æshareholder valueÆ is an important distinction upon which some resource companies are now firmly focussed. The equity market/commodity market cycle can provide windows of opportunity to consolidate and expand a company for the benefit of shareholders. These benefits may not be reflected until more buoyant equity markets return but, as the cycle turns, as it surely will, those with the foresight to position themselves may be richly rewarded.

Jan 1, 2000

Stereological transformation relies on knowledge of the textural characteristic that governs the relationship between the one-, two- and three-dimensional liberation spectrum. Transformation functions can be built from fractionation of real mineralogical particles. Alternatively, transformation functions can be built from simulated textures, geometrical textures or artificial textures. These transformation functions can be useful when the texture of an ore has not yet been characterised for the preliminary assessment of liberation. Recently, Lin et al (1995) developed a methodology for generating such an artificial texture. The artificial texture can be used to produce broken particles of known volumetric composition. Data from image analysis on several artificially generated samples is readily available, and can be used to build the associated stereological transformation function. In this work, the methodology for calculating the transformation function from LinÆs artificial texture is presented. The new texture is implemented for stereological transformation applications.

Jan 1, 2008

The education system today is turning out potential Mine Managers and Superintendents for the coal industry who are lacking in adequate management knowledge. They are required by the Mining Act to be highly skilled operators who are operations and production oriented. This puts them in much the same category as airline pilots and ships' captains. The real need is for them to be management and profit orientated. Changes over the years in Managers' and Superintendents' roles are highlighted by identifying those professions and vocations with whom they must now work. Comparing classifications in the 1916 award and the current award, and making a comparison between management and mining degree courses, leads to the conclusion that separate degree courses are necessary for future Mine Managers and Mining Engineers. Mine management must become a profession in its own right if optimum profits are to be made from mining in the future.

Jan 1, 1980

By Ruffles B. R

A computer simulation has been developed to model the flow of copper ore in Isa Mine. It simulates extraction of copper ore from the 1100 orebody by load-haul-dump (LHD) units to ore passes, haulage from chutes on 19 level by Rockflo trains to crusher bins, crushing and hoisting. It can assess in terms of the tonnage and head grade of ore hoisted, the effect of varying operating strategies, as well as measur- ing shortfalls in required capacities of any of the operations (extraction, hauling, crushing and hoisting). The simulation was designed as a modular, deterministic, steady-state model with parameter input allowing complete flexibility in its use. Queuing theory is used extensively to evaluate the effect of interference at potential bottlenecks. The model has been used to determine the effect on production of varying train sizes, maintenance policies on the haulage circuit, orepass capacities, and extraction operations.

Jan 1, 1974

Record quantities of slag were produced in 1974. Slag usage in this year amounted to 8.5 mega tonnes for granulated blast furnace slag and 7.7 mega tonnes for crushed blast furnace and L.D. slags. Granulated blast furnace slag is mainly used as a hydraulic bonding material in the manufacture of cement and in road construction. These applications give a fuel saving and reduce processing costs. Crushed blast furnace and L.D. slags find application as a substitute for natural aggregates in road construction and in the production of concrete. There is no doubt of ttie interest to utilise to the maximum all the slag produced by the steelmaking industry, thus preventing the build up of slag heaps detrimental to the environment and favouring the disposal of the heaps formed in the past. World wide efforts are being made to achieve this objective.

Jan 1, 1979